The jihadist Islamic State group has posted video of the execution of a captured Kurdish fighter, in a warning to Iraqi Kurdish leaders to end military cooperation with Washington, a monitoring group said.

The United States has carried out a wave of airstrikes against the jihadists in northern Iraq, helping Kurdish forces to claw back ground lost to the militants earlier this month.

The video, titled “A message in blood to the leaders of the American-Kurdish alliance,” opens with 15 men in orange jumpsuits standing around the IS flag.

Three of the men ask Kurdish regional president Massoud Barzani “and the Kurdish government to end their relationship with the US… military intervention in northern Iraq,” the SITE Intelligence Group monitoring service said.

“Any mistake or recklessness from you will lead to the (loss) of our life,” SITE quoted one of the men as saying.

The video then cuts to three masked men dressed in black standing in front of a mosque with another man wearing an orange jumpsuit kneeling in front of them. They then behead him.

Kurdish officials acknowledged the video, but were adamant that it would not deter them from fighting the jihadist group.

“We have lost many men, and maybe we will lose more men, but that will not stop us from implementing our strategy,” Ari Mamshae, a spokesman for Barzani, according to the LA Times.

The video follows another released by IS showing the beheading of American journalist James Foley and threatening another kidnapped reporter Steven Sotloff with the same fate if US airstrikes are not halted.

It also comes hot on the heels of video of scores of bodies that IS boasted were those of Syrian soldiers they had captured and executed following their seizure of a northern key air base last weekend.

The jihadists control a vast swathe of territory straddling Iraq and Syria where their abuses have sparked an international outcry.